[src/trunk]: src/usr.bin/make Make clearfd() take O(1) time instead of O(N) b...

[sommerfeld <sommerfeld%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/4dd95f2c1c2a
branches:  trunk
changeset: 500102:4dd95f2c1c2a
user:      sommerfeld <sommerfeld%NetBSD.org@localhost>
date:      Tue Dec 05 15:28:55 2000 +0000

description:
Make clearfd() take O(1) time instead of O(N) by moving only the last
job in the arrays to the hole made by the now-dead job.  No
measureable performance difference for -j4, but the code is simpler
this way.

diffstat:

 usr.bin/make/job.c |  16 +++++++++-------
 1 files changed, 9 insertions(+), 7 deletions(-)

diffs (44 lines):

diff -r 170dfa5aa18a -r 4dd95f2c1c2a usr.bin/make/job.c
--- a/usr.bin/make/job.c        Tue Dec 05 15:25:57 2000 +0000
+++ b/usr.bin/make/job.c        Tue Dec 05 15:28:55 2000 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: job.c,v 1.37 2000/12/05 15:20:10 sommerfeld Exp $      */
+/*     $NetBSD: job.c,v 1.38 2000/12/05 15:28:55 sommerfeld Exp $      */
 
 /*
  * Copyright (c) 1988, 1989, 1990 The Regents of the University of California.
@@ -39,14 +39,14 @@
  */
 
 #ifdef MAKE_BOOTSTRAP
-static char rcsid[] = "$NetBSD: job.c,v 1.37 2000/12/05 15:20:10 sommerfeld Exp $";
+static char rcsid[] = "$NetBSD: job.c,v 1.38 2000/12/05 15:28:55 sommerfeld Exp $";
 #else
 #include <sys/cdefs.h>
 #ifndef lint
 #if 0
 static char sccsid[] = "@(#)job.c      8.2 (Berkeley) 3/19/94";
 #else
-__RCSID("$NetBSD: job.c,v 1.37 2000/12/05 15:20:10 sommerfeld Exp $");
+__RCSID("$NetBSD: job.c,v 1.38 2000/12/05 15:28:55 sommerfeld Exp $");
 #endif
 #endif /* not lint */
 #endif
@@ -3288,11 +3288,13 @@
        Punt("Unwatching unwatched job");
     i = job->inPollfd - fds;
     nfds--;
+    /*
+     * Move last job in table into hole made by dead job.
+     */
     if (nfds != i) {
-       (void)memcpy(&fds[i], &fds[i + 1], (nfds - i) * sizeof(struct pollfd));
-       (void)memcpy(&jobfds[i], &jobfds[i + 1], (nfds - i) * sizeof(Job *));
-       while (i < nfds)
-            jobfds[i++]->inPollfd--;
+       fds[i] = fds[nfds];
+       jobfds[i] = jobfds[nfds];
+       jobfds[i]->inPollfd = &fds[i];
     }
     job->inPollfd = NULL;
 }